Clamp on paper cutting machine



P 1936- F. LAESSKER 2,

CLAMP ON PAPER CUTTING MACHINE Filed May 22, 1935 2 Sheets-Sheet l in venfor By Afforn ey Sept. 15, 1936. LAESSKER 2,054,505

CLAMP on PAPER CUTTING MACHINE Filed May 22, 1935 2 Sheets-Sheet 2 O 30 G0 .70 I20 I50 1'0 Jn Venfor 19y Attorney Patented Sept. 15, 1936 UNITED STATES PATENT OFFICE 2,054,505 CLAIVII. ON PAPER CUTTING MACHINE Fritz Laessker, Chemnitz, Germany Application May 22, 1935, Serial No. 22,874

10 Claims.

The invention relates to improvements on paper cutting machines, by which springs or other elastic means, operated by the driving mechanism, produce the pressure in the clamp to hold the stock during the'cut.

Among the objects of the invention are;

First.-Simple means, which produce a pressure in the clamp during the whole cut, nearly independent of the increasing or decreasing tension of the elastic member, and hold the stock during the cut in the most favorable manner, consisting in: highest pressure at the moment the knife cuts into the stock and decreasing pressure in expiration of the cut.

Second-Further arrangements of the means which allow a high increase of the pressure up to the moment the knife starts the cut for the purpose to have a smooth, quiet and shakeless working clamp.

Third-Means for an improved adjustment of the pressure amount, to meet proper clamping of soft and hard stock. 5

Further objects of the invention and details of mechanism shall appear from the description and the claims which follow.

I attain these objects by mechanism illustrated in the accompanying drawings, in which Fig. 1 is a front view of the machine, showing the clamp, knife and driving mechanism in resting position, wherein the highest paper pileis seen in the machine.

Fig. 2 shows main part of the transforming mechanism in right angle cross section on line [-4 Fig. 1 of the front view.

Fig. 3 is a view of the driving mechanism looking in the direction of arrow 2 in Fig. 1.

Fig. 4 shows the balance mechanism of the clamp in position at the end of the cut clamping the highest paper pile.

Fig. 5 shows the same position of the driving mechanism as in Fig. 4, clamping no stock.

Figs. 6 to 11 inclusive show certain arrangements of the balance mechanism which obtain a pressure variation during the out.

Figs. Git-11a illustrate the variation diagrammatically.

In the paper cutting machine, shown in Fig. 1, the gear I has its bearing on the machine body 2 and is driven over a clutch by an electric motor neither the clutch nor the motor being shown. On a shaft 4 mounted in the frame of the ma chine is a gear 3 having an eccentric 5 integral therewith.

. A connecting rod 6 is secured to the excentric 5 and by pin 1 to a two-arm lever 8. The latter is turnably mounted on pin 9 which is fixed on the machine body 2 (see also Fig. 3). Lever 8 carries pins l and I2 respectively at the free ends of its arms 8 and 85. Rotation of the excentric produces a swing motion of lever 8 5;; which drives with the pin 10 the knife I I and with the pin l2 the clamp.

The knife II is slidably mounted in the ma chine body 2 above the table 13 which is part of the machine body and carries the paper pile I 4. 19, Usually themovement of the knife takes place in an angle of about 45 degrees to the table. Therefore, the knife II has slots 15, arranged in this angle, and sliding blocks l6, mounted on pins ll which are fixed to the machine-body 2, fitting 1Q; in these slots I5 and guiding the knife.

The connecting rod I8 is pivoted by ID to the lever 8, by 19 to the knife ll. One revolution of the excentric 5 causes a complete downward cutting and upward return motion. The press beam 2Q 20 is movable in a right angle direction to the table surface and mounted (see Fig. 1) behind the knife ll. Connected by pins 25, the press beam is carried by connecting-rods 26, which are pivoted by pins 21 to transmitting-levers 28 and 29. These levers are turnably mounted on pins 30 and 3| which are fixed to the machine body 2. The connecting rod 32, pivoted to the levers 28 and 29, takes care of a parallel motion of the press beam to the table surface and transmits the pow- 3% er from'lever 28 to lever 29. Spring 33, arranged between lever 28 andpin 34 which is fixed to the machine body 2, carries the weight of the press beam and gives it a soft upward motion, so, that the slot 35 of lever 28 and the pin 36 of the trans- 35. forming lever 3l-fix the limit ofthis upward motion.

I now describe the most important part of the invention, the balance mechanism. It consists (see Fig. 1) of the power-transforming lever 31, the connecting-rods 38, 38, of a hollow shaft 39 with the extension 40 and the compression spring 4|. With pin 36 the transforming lever 3! is' secured to the transmitting lever 28. The transmitting lever 3'I'is also pivotally connected to the head 46 is turnably secured to the transforming The shaft 40 is slidably 0 lever 31, and its distance to the pin 42 is also adjustable by hand (see Fig. 2). For this purpose the arms 31" of the transforming lever have slots 48 and a bushing 49 as bearing for head 46 is slidably mounted in the slots 48. A headscrew 50 going through the bushing 48 and the slots 48 can be tightened by a nut 5I, so, that the bushing 49 is fixed at the desired distance from the pin 42. Head'46 is always turnable on the bushing). The operation of the clamp of the above described paper cutting machine may be explained as follows: Pin I2 of the two-arm lever 8 receives by turn of 180 degrees of the excentric 5 a motion, giving it the position as shown in Figs. 4 and 5. The tension of the elastic member during this motion depends on the height of the paper pile. Fig. 4 gives the position of the single parts of the balance mechanism, clamping the highest pile of stock, which is designated by reference character I4 in Fig. 1. Then the press-beam 20, the connecting rods 26 and the transmitting lever. 28, 29 cannot take part in the motion of the lever 8. Hence spring .4I'is pressed together by turn of the transformer lever 31 around the pin 36, and around pin 42. This turn is obtained by motion of the connection rods 38, respectively by excentric 5. .Without any pile on the table I3, Fig. 5 shows this position of parts of the balance mechanism. There is the same, not increased tension of the. spring 41 as in Fig. 1.

of Fig. 5 the press beam 20, the transmitting lever, connecting-rods and elastic member share in the motion of the drivingexcentric 5. It is to be understood, that the press-beam 20 starts its starts its action. The spring is pressed more together and the pile under pressure, no matter what the height of the pile between zero and the maximum. The spring tension increases after this meeting, until a turn of 180 degrees of the'excentric 5 is obtained.

The down motion of the knife will start also with the turn of the driving-excentric and be'flnished with 180 degrees of its turn. It follows: the knife and the clamp are working in the same phase. It is necessary that the cut starts not before the stock is pressed hard enough by the clamp, as to be unmovable. To obtain this certain time difference between the beginning of pressure on the pile and the starting of the cut, arrangements in the driving mechanism of the knife are provided. The arm 8" of the two-arm lever 8 and the connecting 'rod I8 therefore include, at their restposition (see Fig. 1) an angle of about 180 degrees, which decreases with the turn of the excentric to about 90 degrees. With the start of the turn of excentric '5, the lever 8 receives-a motion whose speed is transmitted directly to the clamp by the fact of the direct driv-' ing positions of the levers 8', 28 and 29. But the 'speed of lever 8 is transmitted to the knife II by connecting-rod I8 in an'increasing ratio, until lever 8 has its about rightangle position to connecting rod I8 at 180 degrees turn of the driving excentric, that is to say, during the beginning of the down-motion of the clamp the knife goes 'down with a lower speed and stands back to the motion of the clamp. Because the speed of the knife increases, clamp and knife reach their lowest position (the table) about the same moment.

, It very advantageous, that the knife starts the cut at the moment of the highest pressure in the In ,this case clamp, which is obtained by this described driving mechanism of the knife and the clamp.

Both, the knife and clamp, are moved back to its rest position by turn of the excentric 5 from 180 to 360 degrees. The rest-position is shown in Fig. 1.

The transmitting-lever 28 is provided with a slot 35 which is a section of a circle. The slot allows a down movement against the tension of spring 33. This movement is wanted to "control the distribution'of the'lines with one side of the press beam.

' As to show clearly the single advantages and possibilities of the invention and how the transformed pressure is obtained, the further description shall be made on the diagrammatical views of Fig. 6 to 11, where all unnecessary parts of the cutting machine are omitted.

-In'Fig.,.6 the transmitting lever I28 replaces lever 28 of Fig. l; transforming-lever I31, cor 1-' necting-rod I38, shaft I39 and spring I4' I are-in the place of parts 31, 38, 39 and 41 of Fig. 1 In gram Fig. 6a shows in directionjof arrow P the pressure amount appearing in the press beam, and in direction T the turning degree of driving excentric I 05. pile the spring tension increases from the amount to ,1", see line I60, the arm I31" of the transforming lever decreases its effective arm lengthfrom g'to g','and the arm'I3I' keeps about 'its' effective length 71.. The torque, produced'by the spring tension and the arm of spring attack is alike the torque obtained by the arm of pressure transmission and the pressure in the clamp.

f.g= h.P at zero position of excentric I05 ,f'.g:h.p at 180 degrees position of excentric I05 In the sample of Fig. 6 the spring tension in-- creases from f=100% to f=200%, and the eifec tive length of arm g=100% decreases to g=50%.

That means, at the zero and 180 degrees positions of the excentric I05 the pressure in the transmitting lever I28 is equal, as indicated by line I6I Fig. 6a. The measurement of spring tension ,fand length of the arms g and h. at all positions of the driving excentric I05 between zero and 180 de grees, and between 180 and 360' degrees, shows* pressure in the clamp as indicated by line' I6I.

Fig. 7 shows a different arrangement of the balance mechanism, whereinthe two arms'231" and 231 of the transforming lever change both their efiective lengths g and h in relation-to the turn of the driving excentric 205. Working with the same tension of the spring as insarnple of Fig. 6, the pressure in the clamp has the amount shown at line 26I. At 0 degree the pressure has the amount P, at 45 degrees the maximum P" and will decrease to 'P' at 180 degrees. The knife cuts into the material at thismaximum pressure, which is very advantageous, and be-' cause the expiration'o'fthe out can be done with less pressure, the cut will be finished with decreasing pressure in the clamp, which is'obtained During the out of the highest pressibeam, the effective arm length i of the lever 363 decreases to i', which will produce a decreasing pressure in the clamp as shown by 'P' and'pat line '362 Fig. 8a.. In directionH is marked the height of the piles from zero to maximum, and'line 364 indicates the meeting of clamp and pile for all heights of piles. 'Ab'ove line 364, Fig.8; line 362 shows the amount of pressure at these meeting positions. Line 262, Fig. 8a, represents the pressure amount at the meeting positions or a clamp formed like Fig. '7.

In Fig. 9 is a two-arm lever arranged between the driving excentric 405 and the balance mechanism. The spring tension f is here in rest position very low and will increase with the turn of the excentric, but not reach the amount of the maximum pressure in the clamp. This object, to obtain a maximum pressure as provided in Fig. 6, but with a highest spring tension of only about one half of Fig. 6 is the result of the arrangement of transforming lever 431. Its effective arm lengths g and h, with the above described spring tension, result in the pressure in the clamp as shown by line 46L Up to 45 degrees the pressure is increased from P to P" of more than the double amount, which gives a smooth and shakeless working clamp.

A further object of the invention is shown in Figs. 10 and 11. For proper clamping of hard and soft stock the pressure amount must be adjustable. A pressure variation is obtained in Fig. 10 by varying the absolute length of arm 53'!" from k to k of the transforming lever. This can be done easily, not under the load of the spring tension, by moving the pin 550 in a slot 548 of the lever 531. The movement can be done by hand and the pin 550 tightened with a screw at the wanted position as described in Fig. 1, or a transportation screw with a hand wheel could be used to change the distance of pin 55!] and pin 542. A constant spring tension at rest position of the machine combined with the adjustability of arm 53'! allows a pressure variation as shown between lines SM and 56l', respectively between line 56I and zero.

In Fig. 11 the length of the arm 628 of the transmission lever is adjustable from I to I, with about the same result as described at Fig. 9. Pin 636 can be moved in slot 648. Lines Efil and 6B! are showing the limits of pressure variation in the clamp by an adjustment of one half of the length of arm 628.

In both cases, as described in Figs. 10 and 11, it is an important feature, that the variation of the absolute arm length of a lever takes place without, or nearly without, a movement of the press beam in rest position of the machine. This is obtained by the arrangement of the slot in about the direction of the circle direction, in which the pin 55!) or 636 can be moved, which means: in about right angle a to the spring 54! in Fig. 10 or to the connecting rod 638 in Fig. 11.

I claim as my invention:

1. In a paper cutting machine having a driving mechanism and a paper clamp, a connecting rod and an elastic member each connected to said driving mechanism, a lever to different points of which said rod and said elastic member are operatively connected, and means for reciprocating the clamp actuate-d by said lever.

2. In a pressure balancing mechanism for a paper cutting machine, having a driving mechanism and a paper clamp, an angular lever, a rigid connecting rod connected to said lever at one point thereof and to the driving mechanism,

an'elastic connection-between another point of said lever and the driving mechanisma'nd means for transmitting motion from a third point of said lever to said clamp. I

3. In a paper cutting machinehaving a paper clamp and a driving mechanism, a two-arm lever; rigid means-connecting said lever to: the driving mechanism, a connection of variable lengthconnecting said two-armed lever-to said driving mechanism, a compression spring tending to lengthen saidvariable connection and means for transmitting motion from said twoarmed lever to the clamp, the arrangement being such that difference in the tension of the spring is compensated by variations of the effective length of the arms of the lever which is obtained by turning the lever.

4. In a paper cutting machine, a lever pivoted to the frame of said machine, means for oscillating said lever, a cutting blade and a press bar, means for actuating said blade from one arm of said lever, means for actuating said press bar from another arm of said lever, said last named means comprising a second lever pivoted on the frame of the machine, a floating lever slidably pivoted thereto, a rigid connecting rod pivoted to said floating lever and to an arm of said first named lever and a shaft of telescoping sections pivoted to said floating lever and to the arm of said first named lever to which the rigid connecting rod is pivoted, and a coil spring on said shaft tending to extend said shaft toits maximum length.

5. The device as claimed in claim i, and means on said shaft for regulating the maximum and minimum length of said shaft.

6. The device as claimed in claim 4 wherein there are means for adjusting the point of connection of said shaft to said floating lever.

7. In a paper cutting machine, a cutting blade, a press beam, a two armed lever mounted on the frame of the machine, means operatively connecting said cutting blade to one arm of the lever, and both elastic and rigid means connecting the other arm to a floating lever and operative connections between said floating lever and said press beam.

8. A paper cutting machine comprising a frame, a table mounted in said frame for supporting the paper to be cut, a cutting blade slidably mounted in'the frame, a press beam supported above the table, a two-armed lever, means for oscillating said lever, operating connections between one arm of said lever and the cutting blade, operating connections between the other arm of said lever and the press beam, said last named operating connections including a floating lever, a connecting rod of fixed length pivotally connected to one point of said floating lever and to one arm of the two-armed lever, a shaft of two telescoping parts pivotally connected to another point of said floating lever, and to the same point of said two-armed lever as the connecting rod, a compression spring surrounding said shaft and tending to elongate the shaft, a three armed lever pivoted on said frame and having a slot in which a pin on the floating lever is slidable, a link pivotally connected to one arm of said three armed lever and to one end of the press beam, a bell crank lever pivoted to said frame, a second link pivoted to the bell crank lever and to the other end of the press beam, a shaft connecting said bell crank lever to the three armed lever to guide the motion of the links and a springsecured to said frame and to the three armed lever tending to hold said press beam in an elevated position.

ing to elongate said telescopic extensible rod, the arrangement and construction being such that in the lowest position the telescopic rod makes an angle of substantially 90with the arm of the second named lever and the connecting rod makes an angle of less than 45 with its arm of the second namedlever and the first said angle decreases while the second said angle increases with the operation of the mechanism from this position.

Fnrrz LAESSKER. 

